Method for improving engine performance using a temperature managed fuel system

Abstract

A method to operate an internal combustion engine having a fuel delivery system and a heat exchanger located to affect a fuel temperature within the fuel delivery system includes monitoring a desired heat transfer between a flow through the heat exchanger and fuel within the fuel delivery system, determining a required flow through the heat exchanger based upon the desired heat transfer, and controlling a flow control device for the heat exchanger based upon the determined required flow.

The invention claimed is: 
     
       1. A method to operate an internal combustion engine comprising a fuel delivery system and a heat exchanger located to affect a fuel temperature within the fuel delivery system, the method comprising:
 monitoring a desired heat transfer between a flow through the heat exchanger and fuel within the fuel delivery system; 
 selecting one of a plurality of flows through the heat exchanger based upon the desired heat transfer between a flow through the heat exchanger and fuel within the fuel delivery system, the plurality of flows including a flow to heat the fuel within the fuel delivery system and a flow to cool the fuel within the fuel delivery system; 
 determining a required flow rate of the selected one of the plurality of flows through the heat exchanger based upon the desired heat transfer; and 
 controlling a flow control device for the heat exchanger based upon the determined required flow rate. 
 
     
     
       2. The method of  claim 1 , wherein the flow through the heat exchanger is an engine coolant flow heating the fuel within the fuel delivery system. 
     
     
       3. The method of  claim 1 , wherein the flow through the heat exchanger is a heated intercooler fluid flow heating the fuel within the fuel delivery system. 
     
     
       4. The method of  claim 1 , wherein the flow through the heat exchanger is a supply intercooler fluid flow cooling the fuel within the fuel delivery system. 
     
     
       5. The method of  claim 1 , wherein the flow through the heat exchanger is an exhaust gas flow heating the fuel within the fuel delivery system. 
     
     
       6. The method of  claim 1 , wherein the flow through the heat exchanger is an engine coolant flow from a coolant loop having received heat from an exhaust gas heat exchanger, the engine coolant flow heating the fuel within the fuel delivery system. 
     
     
       7. The method of  claim 1 , wherein the flow through the heat exchanger is an engine coolant flow from a coolant loop having received heat from the fuel within the fuel delivery system and expelling heat through a dedicated radiator device. 
     
     
       8. The method of  claim 1 , wherein monitoring a desired heat transfer comprises:
 measuring fuel temperature; and 
 determining a feedback control of the flow rate through the heat exchanger based upon the fuel temperature. 
 
     
     
       9. The method of  claim 1 , wherein monitoring a desired heat transfer comprises:
 monitoring operation of the engine; and 
 determining the desired heat transfer based upon the monitored operation of the engine; and 
 wherein determining a required flow rate through the heat exchanger based upon the desired heat transfer comprises:
 monitoring an estimated state of the selected flow available to the heat exchanger; and 
 determining the required flow rate through the heat exchanger based upon the estimated state of the selected flow available to the heat exchanger and the desired heat transfer. 
 
 
     
     
       10. The method of  claim 9 , wherein monitoring the estimated state of the flow available to the heat exchanger comprises:
 modeling operation of an engine cooling system. 
 
     
     
       11. The method of  claim 9 , wherein monitoring the estimated state of the flow available to the heat exchanger comprises:
 modeling operation of an intercooler fluid circuit. 
 
     
     
       12. The method of  claim 1 , wherein controlling the flow control device for the heat exchanger based upon the determined required flow rate of the selected one of a plurality of flows comprises controlling a plurality of flows through the heat exchanger. 
     
     
       13. A method to operate an internal combustion engine comprising a fuel delivery system and a heat exchanger located to affect a fuel temperature within the fuel delivery system, the method comprising:
 monitoring a desired fuel temperature; 
 monitoring a measured fuel temperature; 
 selecting one of a plurality of flows through the heat exchanger based upon the desired fuel temperature and the measured fuel temperature, the plurality of flows including a flow to heat the fuel within the fuel delivery system and a flow to cool the fuel within the fuel delivery system; 
 determining a required flow rate of the selected one of the plurality of flows to the heat exchanger based upon the desired fuel temperature and the measured fuel temperature; and 
 controlling a flow to the heat exchanger based upon the required flow. 
 
     
     
       14. The method of  claim 13 , wherein the desired fuel temperature is greater than the measured fuel temperature. 
     
     
       15. The method of  claim 13 , wherein controlling the flow to the heat exchanger comprises controlling a coolant flow control valve. 
     
     
       16. The method of  claim 13 , wherein the desired fuel temperature is between eighty five degrees Celsius and ninety degrees Celsius. 
     
     
       17. The method of  claim 13 , wherein monitoring the desired fuel temperature comprises:
 monitoring a current combustion mode; 
 determining a desired fuel spray pattern based upon the current combustion mode; and 
 determining the desired fuel temperature based upon the desired fuel spray pattern. 
 
     
     
       18. The method of  claim 17 , wherein monitoring the current combustion mode comprises determining the current combustion mode to be a combustion mode sensitive to preignition; and
 wherein determining the desired fuel spray pattern comprises selecting a desired spray pattern including altered penetration based upon the combustion mode sensitive to preignition. 
 
     
     
       19. The method of  claim 17 , wherein monitoring the current combustion mode comprises determining the current combustion mode to be a combustion mode sensitive to a condition selected from the group consisting of low combustion stability, high soot emission, and slow combustion phasing; and
 wherein determining the desired fuel spray pattern comprises selecting a desired spray pattern including reduced penetration based upon the combustion mode sensitive to the condition. 
 
     
     
       20. The method of  claim 13 , wherein monitoring the desired fuel temperature comprises:
 monitoring a required volumetric efficiency; and 
 determining the desired fuel temperature based upon the required volumetric efficiency. 
 
     
     
       21. An apparatus to operate an internal combustion engine comprising a fuel delivery system and a heat exchanger located to affect a fuel temperature within the fuel delivery system, the apparatus comprising:
 the fuel delivery system comprising a fuel rail; 
 the heat exchanger located to affect the fuel temperature within the fuel rail; 
 at least one flow circuit connected to the heat exchanger, the at least one flow circuit comprising a flow control device; 
 a plurality of flows to the at least one flow circuit, the plurality of flows including a flow to heat the fuel within the fuel delivery system and a flow to cool the fuel within the fuel delivery system; and 
 a control module. 
 
     
     
       22. The apparatus of  claim 21 , wherein the flow circuit comprises a flow of intercooler fluid. 
     
     
       23. The apparatus of  claim 21 , wherein the flow circuit comprises a flow of engine coolant. 
     
     
       24. The apparatus of  claim 21 , wherein the control module:
 monitors a desired fuel temperature; 
 monitors an actual fuel temperature; 
 selects one of the plurality of flows to the at least one flow circuit based upon the desired fuel temperature and the actual fuel temperature; 
 determines a required coolant flow rate of the selected one of the plurality of flows to the heat exchanger based upon the desired fuel temperature and the measured fuel temperature; and 
 controls the flow control device based upon the required coolant flow rate. 
 
     
     
       25. The apparatus of  claim 21 , wherein the control module:
 maintains a flow from the flow circuit within the heat exchanger through a hot soak period.